This study looks at the dynamic tendon-to-bone contact properties of rotator cuff (RC) repairs—comparing single row repairs (SRR) with double row transosseous- equivalent (TOE) repairs. It was postulated that relaxation during, and movement following, the repair would significantly compromise contact properties and therefore, the ability of the tendon healing.

Simulated tears were created in the supraspinatus tendon of six cadaveric human shoulders. A SRR was then performed using the OPUS System, creating two horizontal mattress sutures. An I-Scan electronic pressure-sensor (Tekscan, Boston, MA) was placed between the supraspinatus tendon and bone. The arm was then rested for 300secs (relaxation) before being passively moved twice through a range-of-motion (0-90 degrees abduction, 0-45 external and 0-45 internal rotation) and finally returned to neutral. The contact properties were recorded throughout each movement. The procedure was then repeated using two TOE techniques: parallel sutures (TOE-P) and a cross over suture pattern (TOE-C).

While peak pressures during the repair were higher in the two TOE repairs, all three methods demonstrated relaxation over 300s such that there was no significant diference in contact pressures at the end of this time. TOE parallel and cross-over repairs demonstrated no significant change in mean TTB contact pressure, force and area during abduction, external rotation and return to neutral, when compared to the 300sec relaxation state. TOE-C demonstrated a higher contact force on internal rotation (+53%). The SRR demonstrated a significant drop in contact force on abduction (−63%), and return to neutral (−43%) and a trend on external rotation (−34%). SRR exhibited no change on internal rotation.

There have been very few biomechanical studies with which observe RC repair contact properties dynamically. Relaxation of the repair can be partially reversed. Significant decrease in contact area with SRR during movement occurred, compared to the TOE repairs, which remains unaltered. This is an important consideration when determining postoperative rehabilitation.

Rotator cuff repair failure may to some extent be attributed to tendon-bone gap formation at the repair sight caused by insufficient suture tightening. We measured the footprint contact properties over time of single row and trans-osseous equivalent repairs. We also investigated the effect of suture retightening on the repair.

Rotator cuff tears (RCT) were created in the supra-spinatus tendon of 6 cadaveric shoulders. An electronic pressure sensor (Tekscan) was placed between the tendon and bone to measure the footprint pressure. The OPUS AutoCuff System was used to consecutively repair the RCT using a single row repair (SR-R) and two trans-osseous equivalent repair (TOE-R) techniques;

two parallel sutures (TOE-P) and

Peak initial contact force, were recorded on suture tightening (peak force) and equilibrium contact properties after 300 seconds relaxation (equilibrium force). Data were analysed using pairwise ANOVA.

All techniques demonstrated a similar trend in the contact properties over the test period with an initial peak in contact force on tightening of the sutures, followed by a rapid drop in contact pressure immediately after suture tightening, and finally tending towards equilibrium contact force at 300 seconds.

The TOE-C group demonstrated the highest mean ‘peak force’ and the highest ‘equilibrium force’ after 300 seconds relaxation. The TOE-P ‘peak force’ and ‘equilibrium force’ were −15% and −3% that of TOE-C, while the SRR was −45% and −25% that of TOE-C.

Retightening the sutures a second time had little effect on the SSR contact properties, while retightening the TOE repairs increased the equilibrium contact force by 30% although this was not significant.

Significant relaxation occurs especially within the first 30s, compromising the contact properties.

TOE-R’s exhibit better contact properties than SRR. Retightening the TOE-R’s tended towards a higher final equilibrium contact force. SRR repair contact properties were unaffected by a second tightening.

TOE-R’s should be re-tightened before the suture is locked

Introduction: Stress fractures comprise a major problem in female police or army recruits. The incidence of stress fractures is reported ranging from 3 to 10 fold when compared to male recruits taking the same training program. This study consisted of an intervention program aiming at reducing combat gear weight and locating the gear as close as possible to the body center of gravity.

Material and Methods: In a prospective study we followed up two companies of female recruits of the Israel Border Police. Both companies were followed for the four months of basic training using a basic data questionnaire inclusive of previous physical activity habits, previous acute and overuse injuries, menstrual history and previous smoking habits. An injury questionnaire was filled on commencement of the course and every two weeks thereafter. The clinical records of medic and doctor visits, as well as the personal medical file, were revised. Roentgenological and scintigraphic imaging were performed during the course, when clinical suspicion of a stress fracture arose.

The first company of 71 fighters used the standard combat gear amounting to 12.5 kg. The second company of 64 fighters used combat equipment weighing 9.4 kg, held in a combat girdle close to the body center of gravity, inclusive of a shorter personal combat riffle and personal combat vest.

Results: There was no difference in the number of clinic visits between the two companies. Complaints suggesting stress fractures were recorded in the first company from the 3^rd to the 8^th week of training and in the second from the 1^st to 3^rd week. The percentage of fighters sent for Scintigraphy because of clinical suspicion of stress fractures was 22.5% in the first company and 6.25% in the second. The percentage of fighters in whom stress fractures were located by Scintigraphy was 15.5% in the first company and 4.7% in the second. The number of stress fractures in average per fighter was 0.45 fractures in the first company and 0.27 fractures in the second. When calculating only “dangerous” stress fractures (long bones and navicular) there were noted 0.34 fractures per fighter in the first company and 0.20 in the second. Total average training days lost for reason of stress fractures was 2.21 per fighter in the first company and 1.08 in the second.

Conclusions: Reducing the weight of the fighting gear and securing it closer to the body center of gravity may have a positive effect in reducing the incidence of stress fractures in female recruits of fighting units during the intense basic training program.